SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '476e3e6fbed1132e5f2f6083225a716efabca652d40915b5cbd3ca455b762cb1' 
  AND token = 'YJUZgrChSns2xcYYJkfJt8B14b03pR7ddpaTiLJmxiA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}